A fuel cell comprises a fuel electrode and an air electrode sandwiching an electrolyte. A fuel gas or the like is supplied to the electrodes to generate electricity. In a solid oxide fuel cell (SOFC), in particular, a fuel electrode (hydrogen electrode) and an air electrode (oxygen electrode) are joined to an electrolyte made of a solid oxide. The fuel electrode is supplied with a fuel gas and the air electrode is supplied with air or the like, whereby high-output electric power can be generated. The solid oxide fuel cell can use, as the fuel gas, not only hydrogen gas but a gas containing a large amount of carbon monoxide (e.g., exhaust gas of a motor vehicle driven by an internal combustion engine).
Patent Document 1 discloses a solid oxide fuel cell with a cylindrical shape. In the fuel cell of Patent Document 1, pipe joints are screwed directly on the fuel cell to connect a gas tank to the fuel cell.
In this type of fuel cell, however, a porous solid is used for both the fuel and air electrodes, and therefore, a problem of strength arises if the electrodes are disposed in direct contact with other members. Specifically, the electrodes may possibly be damaged after a long period of use.